Along the period `(rarr)` atomic`//`ionic radii and metallic character decreases while `IE`, `EN` , non-metallic character and oxidising power increases. Down the group `(darr)`, atomic`//`ionic radii, metallic character and reducing character increase while `IE` and `EN` decrease. However, `Delta_(eg)H^(ɵ)` becomes less negative down a group but more negative along a period.
Correct order of `IE_(2)` of the following is

Options

A. `F gt O gt N gt C`
B. `O gt N gt F gt C`
C. `O gt F gt N gt C`
D. `C gt N gt O gt F`.

Answer

To determine the correct order of the second ionization energy (IE₂) for the elements carbon (C), nitrogen (N), oxygen (O), and fluorine (F), we need to analyze their electronic configurations and the trends in ionization energy across the periodic table.

### Step-by-Step Solution:

1. **Understand the Electronic Configurations**:
- Carbon (C): 1s² 2s² 2p²
- Nitrogen (N): 1s² 2s² 2p³
- Oxygen (O): 1s² 2s² 2p⁴
- Fluorine (F): 1s² 2s² 2p⁵

2. **Identify the First Ionization Energy (IE₁)**:
- The first ionization energy is the energy required to remove the outermost electron from a neutral atom. As we move from left to right across a period, the ionization energy generally increases due to increased nuclear charge.

3. **Consider the Second Ionization Energy (IE₂)**:
- The second ionization energy is the energy required to remove a second electron after the first has already been removed. The stability of the resulting ion plays a crucial role in determining this value.

4. **Analyze Stability of Ions**:
- After the first ionization:
- C⁺: 1s² 2s² 2p¹ (relatively stable)
- N⁺: 1s² 2s² 2p² (more stable than C⁺)
- O⁺: 1s² 2s² 2p³ (half-filled configuration, stable)
- F⁺: 1s² 2s² 2p⁴ (less stable than O⁺)
- For the second ionization:
- C²⁺: 1s² 2s² (stable)
- N²⁺: 1s² 2s² 2p¹ (less stable)
- O²⁺: 1s² 2s² 2p² (unstable due to removal from half-filled)
- F²⁺: 1s² 2s² 2p³ (stable)

5. **Order of IE₂**:
- The stability of the resulting ions indicates that the second ionization energy will be highest for oxygen due to its half-filled configuration, which requires more energy to remove an electron.
- The order of increasing second ionization energy is:
- C < N < F < O

### Final Order of IE₂:
The correct order of second ionization energy (IE₂) is:
**C < N < F < O**